1. Field of the Invention
The present invention relates to a swash plate for a swash plate-type, variable displacement compressor for use in an automobile air conditioning system. More particularly, it relates to a boss of the swash plate.
2. Description of Related Art
A known boss of a swash plate for a swash plate-type, variable displacement compressor for use in an automobile air conditioning system is penetrated slidably by a drive shaft, and is connected slidably to a rotor fixed to the drive shaft. The boss has a penetration hole penetrated by the drive shaft, within which the drive shaft slides axially when the compressor is working under a heavy load. Consequently, the portion of the boss surrounding the penetration hole has a high degree of hardness. Therefore, in such bosses, the portion of the boss surrounding the penetration hole may be hardened by an induction hardening process or the whole of the boss may be hardened by carburizing.
If only a portion of the boss surrounding the penetration hole is hardened by the induction hardening process, the whole of the boss is made of a relatively hard material to endure the induction hardening process. However, it may become difficult to process such a boss made substantially of a relatively hard material. Moreover, in such case, the boss may become deformed because the boss is hardened only on the portion of the boss surrounding the penetration hole by induction hardening. Similarly, when the whole of the boss is hardened by carburizing, the boss may become deformed because the boss is heat-treated at a relatively high temperature. Thus, when the boss is connected securely by press-fitting within the body plate of the swash plate, the inserted portion of the boss may require reprocessing in order to restore it to its original shape because a high degree of precision is required in assembling the parts of a swash plate-type compressor. In addition, when only the portion of the boss surrounding the penetration hole is hardened by induction hardening, the inserted portion of the boss may be of the same hardness as that of the body plate because the inserted portion of the boss may not be heat-treated. Therefore, the inserted portion of the boss may bite against the body plate when the inserted portion of the boss is inserted within the body plate, and, consequently, the boss may not connect securely within the body plate.
Therefore, a need has arisen for a boss of a swash plate for a swash plate-type variable displacement compressor for use in an automobile air conditioning system that overcomes these and other shortcomings of the related art. It is technical advantage of the present invention that it facilitates the processing of the boss and that it allows the boss to connect more precisely within the body plate. In particular, the boss may connect securely by press-fitting within the body plate.
In an embodiment, this invention is a swash plate for a swash plate-type, variable displacement compressor, such that the compressor is driven by a drive shaft having a shaft axis. The swash plate comprises a boss that is penetrated slidably by the drive shaft. The boss is connected slidably to a rotor that is fixed to the drive shaft, whereby a variable, oblique angle is formed between a surface of the swash plate and the shaft axis. The boss is connected securely within the swash plate and comprises a nitrided surface layer, e.g., a layer of steel containing nitrides.
In another embodiment, this invention is a swash plate for a swash plate-type, variable displacement compressor, such that the compressor is driven by a drive shaft having a shaft axis. The swash plate comprises a boss that is penetrated slidably by the drive shaft. The boss is connected slidably to a rotor that is fixed to the drive shaft, whereby a variable, oblique angle is formed between a surface of the swash plate and the shaft axis. The boss is connected securely within the swash plate and comprises a sulfur nitrided surface layer, e.g., a layer of steel containing compounds of sulfur, nitrogen, and a metal.
In still another embodiment, this invention is a swash plate-type, variable displacement compressor is driven by a drive shaft having a shaft axis. The swash plate comprises a swash plate and a boss. The boss is penetrated slidably by the drive shaft and is connected slidably to a rotor that is fixed to the drive shaft, whereby a variable, oblique angle is formed between a surface of the swash plate and the shaft axis. The boss is connected securely within the swash plate and comprises a nitrided surface layer, e.g., a layer of steel containing nitrides.
In yet another embodiment, this invention is a swash plate-type, variable displacement compressor is driven by a drive shaft having a shaft axis. The swash plate comprises a swash plate and a boss. The boss is penetrated slidably by the drive shaft and is connected slidably to a rotor that is fixed to the drive shaft, whereby a variable, oblique angle is formed between a surface of the swash plate and the shaft axis. The boss is connected securely within the swash plate and comprises a sulfur nitrided surface layer, e.g., a layer of steel containing compounds of sulfur, nitrogen, and a metal.
In a further embodiment of this invention, a method for manufacturing a swash plate for a swash plate-type, variable displacement compressor is described. The compressor is driven by a drive shaft having a shaft axis. The swash plate comprises a boss that is penetrated slidably by the drive shaft. The boss is connected slidably to a rotor that is fixed to the drive shaft, whereby a variable, oblique angle is formed between a surface of the swash plate and the shaft axis. The method comprises the steps of connecting the boss securely within the swash plate and surface hardening by nitriding the boss, e.g., a layer of steel containing nitrides.
Other objects, features, and advantages of embodiments of this invention will be apparent to, and understood by, persons of ordinary skill in the art from the following description of preferred embodiments with reference to the accompanying drawings.